<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script>
    var str = "hello world";
    var arr = new  Array;
      Array=str.split("");
    for(var i=Array.length-1;i>=0;i--){
        document.write(Array[i]);}
    console.log(Array)
</script>
<!--<script>
    var arr = [1,2,1,3,4,5,3,5,4,2,4,1,5,1,5]
    arr.sort();
    indexOf函数
    reverse反转

</script>-->
</html>